JPS6010594B2 - nuclear power plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear power plant, and in particular to a nuclear power plant that is capable of securing the feed water flow necessary to remove decay heat even after an accident such as a turbine trib or reactor scram. Regarding power plants.

・In general, in this type of plant, an electric-driven main water pump is used to supply water to intermediate heat exchangers, etc. for small-sized plants, and a steam-driven condensing turbine is used for larger plants to improve efficiency. There is.

The water pump using the steam-driven condensing turbine described above uses the exhaust steam of the high-pressure turbine as its steam source during high-output operation, and switches to the steam upstream of the main shutoff valve of the high-pressure turbine during low-output operation, and uses that live steam. The main water pump drives the turbine. These water pumps are configured to trip at the same time as the turbine trips.

On the other hand, in a nuclear power plant, even in the event of a reactor scram, turbine trip, or power loss accident,
It is necessary to continuously remove the decay heat from the core.

In particular, when a fast reactor has intermediate cycles such as a primary cooling system and a secondary cooling system, it is necessary to intermittently heat up the retained heat between them. However, in the above-mentioned plant, as shown in Figure 2, the water supply of the turtle-driven water pump rapidly decreases with the loss of power, and the water supply is interrupted until the start-up water pump is started with the emergency power supply. or be cut off.

In addition, steam turbine-driven water pumps are operated by switching to live steam at the same time as the turbine trips or the main shutoff valve closes, but due to poor follow-up, the water supply decreases rapidly at one point and takes a long time to stabilize. It takes. Therefore, during this period, necessary water cannot be supplied to the reactor side, resulting in inconveniences such as the inability to safely and stably remove decay heat in the reactor. In view of these points, the present invention provides a nuclear power plant that can secure the necessary water supply flow rate to remove decay heat from the reactor core even in the event of an accident such as a turbine trip or reactor scram. The purpose is to

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic system diagram of the nuclear power plant of the present invention,
The cold soot heated in the reactor 1 is transferred to the intermediate heat exchanger 2.
It exchanges heat with the next medium and is further circulated to the reactor 1 by the primary main circulation pump 3.

Further, the secondary medium heated by the intermediate heat exchanger 2 is sent to the superheater 4 and the reheater 5, and further passed through the evaporator 6 and circulated to the intermediate heat exchanger 2 by the secondary main circulation pump 7. .

On the other hand, the steam heated and generated by exchanging heat with the secondary medium in the evaporator 6 is sent to the steam/water porcelain 8 where it is separated from steam and water, passes through the L superheater 4 and the main blocking valve 9, and is then sent to the high pressure turbine 10. 'This will be supplied.

The steam that has performed work in the high-pressure turbine 10 is sent to the reheater 5, and is sequentially supplied to the intermediate-pressure turbine 12 and the low-pressure turbine 13 through the saiko intercept valve 11, where it performs work in the intermediate-pressure turbine 12 and the low-pressure turbine 13, respectively. After that, the water is condensed in the condenser 14. The condensate condensed in the condenser 14 is sent to the deaerator 17 via the low-pressure feed water heater 16 by the condensate pump 15, and is then sent to the deaerator 17 via the feed water pump 181, the high-pressure feed water heater 19, and again to the evaporator 6. It is circulated to.

The water supply pump 18 is composed of a starting water pump 18a and a main water pump 18b which are connected in parallel to each other.The starting water pump 18a is driven by an electric motor (not shown), and the water pump 18b is driven by an electric motor (not shown). It is configured to be driven by a main water pump driving turbine 20i which is operated by steam branched out from the upstream side of the main blocking valve 9, and the exhaust from the main water pump driving turbine 20 is connected to the condenser. It is made to condense in Kame 4.

On the other hand, an emergency cooling water tank 21 is located above one side of the condenser 14.
A branch pipe 24 from a cooling water supply conduit 23 that supplies cooling water to the condenser 14 by a circulating water pump 22 is connected to the two emergency cooling water tanks via a pump 25. During normal operation, a small flow of cooling water is supplied by the pump 25 to keep the emergency cooling water tank 2 full of water. The emergency cooling water tank 2 is connected to the inlet of the water tank 14 and
1 can be supplied to the condenser 14. In the figure, the flash tank 28 with reference numeral 27' is a flow tank, and the reference numeral 29 is an atmosphere release valve.

When a nuclear reactor scram, turbine trip, power loss accident, etc. occurs, the atmosphere release valve 29 is opened and the steam exiting the superheater 4 is released into the atmosphere.

On the other hand, at the same time as the above-mentioned accident occurs, including the loss of the fin moat, the starting water supply pump turtle 8a is connected to the emergency power source and started.
However, it takes about 3 minutes to 1 minute for the start-up water pump 18a to start up, so during that time the superheater 4
The main feed water pump 18b continues to be driven by the main feed water pump driving turbine 20', which is operated by a portion of the high pressure steam that has exited the steam generator, and the water stored in the deaerator 17 is used as a water source to supply water to the steamer 6. is carried out, and the required cooling of the secondary soot, etc. is carried out. After the superheater 4 is isolated, the steam generated in the evaporator 6 is released into the atmosphere from the blow tank 28 through the flash tank 27 of the steam equipment 8. If the pump 22 trips, the condenser 14 cannot be used as is, but in this case the valve 26 is opened and cooling water from the emergency cooling water tank 21 is supplied to the condenser 14. be combined.

Therefore, the operation of the main water pump driving turbine can be sufficiently continued until the start-up water pump is started and started up, and necessary water can be supplied.

In this way, in the present invention, the main feedwater pump drive turbine is always operated by live steam from the upstream side of the main stop valve, so the feedwater flow rate at the time of the L accident occurs, as shown by the solid line in Figure 2. Changes can be made smoothly, and water supply can be ensured in the event of an accident, and the necessary water supply can be sent to the reactor side.

Moreover, in the present invention, since an emergency cooling water tank is attached to the condenser, even if the condenser circulation pump trips due to power loss, etc., cooling water from the emergency cooling water tank can be supplied to the condenser. supply, allowing the main feed water pump drive turbine to continue operating. Therefore, thermal transient changes occurring on the reactor side can be suppressed to a small level, the reactor can be stopped in a safe and stable state, and structural design conditions for equipment can be relaxed. A simple illustration of the drawings: Figure 1 is a schematic system diagram of the nuclear power plant of the present invention, and Figure 2 is a diagram showing a comparison of changes in water supply flow rate over time.

6...Evaporator 9...Main stop valve, Kamenen...Condenser,
17... Deaerator, 18a... Starting water supply pump, 18b
...Main water supply pump, 20...Main water supply pump drive turbine, 21...Emergency cooling water tank.

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Claims (1)

[Claims] 1. The turbine for driving the main water supply pump is a condensing turbine driven by live steam constantly taken in from the upstream side of the turbine main blocking valve, and the condenser is equipped with an emergency cooling water tank. A nuclear power plant.